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1,6 Aug. 9, 1927. V. CLARK 38,087

EXHAUST MUFFLER Filed May 9, 1925 ,2 Sheets-Sheet 1.

g v. E. CLARK EXHAUST MUFFLER Filed May. 9. 1-925 Patented Au 9, .1921.

" UNITED STATES 1,638,087 PA ENT orricsj vrnemrus a. CLARK, or Darren,- on o, assreuoaro DAYTON-WRIGHT COMPANY, or I Darren, care, A coaronarion'or DELAWARE.

Exrmusr Application filed May 9,

This invention relates to silencers andback pressure reducing means for internal-combustion engines and has for its object to provide an' improved construction thereof which is particularly suitable for use with aircraft engines but can be used with any internalwhirling and so are prevented from reentering the exhaust pipe and building up .the pressure again. The whirling motion of the gases also prevents their suddent efiiux into the atmosphere and evens out their exit velocities whereby the noise is greatly reduced.

A further feature of the invention is the shape of the silencer which gives it small air resistance and a very large cooling surface exposed to the air draft, these properties being especially important when the 11'1V8Il;

tion is used on aircraft. v Further objects and advantages of the present invention will be apparent from the following description reference being bad to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings: f v Fig. 1 shows a muffler built according to this invention applied to an airplane engine. Fig.2 is a longitudinal section through the mufller on line 2-2 of Fig. 3.

Fig. 3 is a transverse section of thesame on line 33 of Fig. 2. Fig. 4 is a section of the inlet pipe to the mufller, being taken on line .44 of Fig. 2. 4 Fig. 5 is a view similar to Fig. 3, but shows a modification. y

Throughout the drawings similar reference characters refer to similar parts.

In Fig. 1, numeral 10 designates eng' e, which is .enclosed under the usual cowling. The mufiler 12 is preferably located inv a low position, as clearly illustrated, e9 the noise at the cockpit will be inae ex'-' haust manifold for the internal-com ustion MUFFLER.

1923. Serial No. 637,827. r

terially decreased and so" that the glareof the exhaust gases during night flylng willnot blind the pilot. The relative position of the mufiler 12 with the wing also renders the muffler more eificient.

casing 13 of preferably stream line outer shape, as clearly shown in Figs. 1 and 2, sa1d casing 13 having through its central port-ion an air passage 14 of an appreciable size, the space between the walls of casing 13 Y and passage 14 thus forming an elongated annular chamber 15. Exhaust gases are led into this chamber 15 in a peripheral direction by means of the inlet pipe 16 which is suitably attached to casing 13 in a tangential or peripheral direction. The pipe 16 is preferably flattened out at the point where it is attached to vcasing 13 so that the exhaust gases will be delivered to chamber 15 in a more or less thin sheet (see Figs. 2, 3 and 4.) The walls of air passage 1 L are provided with a plurality of small holes 20 which may 1 be more or less evenly distributed throughout the entire area of the air passage, however if desired they-may be omitted along the band opposite the inlet pipe 16 if there is a tendency for the exhaust gases to pass directly from pipe 16 through the holes 20 without setting up asuflicienir whirling action. i The action of the muffler will be apparent from the drawings. The exhaust gases'enter chamber 15 from pipe 16at a high velocity at each openin of the engine exhaust valves,

which high ve ocity sets up a violent whirlv ing withinchamber 15. The whirling mass of exhaust gases after entering chamber 15 spreads out laterally toward each end of the chamber and thus has its velocity gradually reduced due to'the eatly increased cross 05 section of path. As t e velocity reduces, the gases gradually pass out the small holes 20 lnto the passa e 14; and thence to the outer atmosphere. The centrifugal action of the whirling gases prevent their sudden efllux through the holes 20 and thus greatly reduces the noise of the exhaust. If desired the air passage 14 may have a Venturi shape in order that the air stream therethrough may create a depression which tends to draw the exhaust gases out of the whirling chamber 15. The outlet holes 20 are preferably turned slightly" down stream, as clearly The muifier 12 is made up of a thin outer 60' the desired shape by inserting a small rod,

stream to raw the exhaust gases therethrough will be increased. The lip or edge I of the holes 20 may be easily bent to give approximately the size of the hole, radially therethrough and then tilting the rod over to press the upstream edge of the hole toward the center of tube 14 and the downstream edge away from the center. Of course the holes 20 could be any desired shape, for instance short slots or long slots extending either in a circumferential direction or in an axial direction of tube 14, The total area of the holes 20 is governed by the amount of exhaust gases to be disposed of by the mufiler. Of course for a greater volume of exhaust gases the total area should be increased to prevent the pressure in chamber 15 from building up too high and yet cause the gases to pass out at a sufiiciently low maximum velocity to give the desired muffling action.

The casing 13 and air passage 14 are preferably made up of thin sheet metaland therefore the air stream on theoutside of casing 13 as "well as that through passage 14. have a great cooling effect upon the exhaust gases in chamber'15'. This cooling action greatly reduces the volume of the exhaust gases and hence increases the silencing effect of the mufller.

The parts of the mufiler may be suitably secured together by welding, as illustrated in Figs. 3, 4 and 5 at the points 25.

Fi 5 is a transverse? section through a modi ed form of muffier. The inlet 30 of the exhaust pipe 16 is flattened out and slightly constricted to speed up the exhaust gases as they enter the whirling chamber 15'. The direction of the entering exhaust gases is also substantially parallel with the gases rotating Within chamber 15' (as shown by p the arrows) and hence the suction efi'ect of 5 the rotating gasesupon the gases within the exhaust pipe 16 will be greatly increased. The lip 31 prevents the centrifugal action of the whirling gases from increasing the pressure at the mouth of the exhaust pipe 16- and thus causing gases to back up within the pipe 16. I

While the form of embodiment of this invention as herein disclosed, constitutes preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

' approximately the What I claim is as follows: 1. In a silencer for an internal-combustio engine, an oval shaped elongated expansion chamber, asingle exhaust pipe leading substantially tangentiall into said chamber at ongitudinal center of said oval, an air assage extending longitudinally through t e central portion of said oval chamber, and a plurality of relatively small exhaust outlets leading from the expansion chamber into said air passage and distributed over a substantial area on both sides-of said central exhaust inlet pi e.

2. In a silencer for an internal-com ustion engine, an oblong expansion chamber, ring-' like in transverse section, means for leading all the exhaust gases substantially tangentiall into said chamberat a proximately the ongitudinal center thereof an air passage extending longitudinally through the central portion of said chamber, and a plurality of relatively small exhaust outlets leading from the expansion chamber into said air passage, said exhaust outlets being distributed on both sides of said centrally disposed exhaust inlet.

3. In a silencer for an internal-combustion engine, an oval shaped chamber, means for leading all the exhaust gases into said chamber substantially at the maximum cross sec- -tion thereof in a peripheral direction whereby a whirling of the exhaust gases is set up within said chamber, and a Venturi shaped air passage wherein a depression is created due to a forward velocity of the silencer, and a pluralit of relatively small exhaust outlets leading rom the inner periphery of said chamber to said air passage. I

4. In a silencer for an internal combustion engine, a whirling chamber elongated in the direction of the axis of the whirling gases, duct means for leading all the exhaust gases into said chamber at approximately the central portion thereof in a eripheral direction whereby a whirling of t 1e exhaust gases is set up within said elongated chamber, a Venturi sha ed air passage leadin axially through sai whirling chamber w erein a depression is created due to a forward ve- 'locity of the silencer, and a plurality of exhaust outlets leading from the inner periphery of said whirling chamber to saidair passage.

In testimony whereof I hereto aflix my signature. 1

V. E. CLARK. 

